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Density of dark matter
Inverse biquadrate force might be proved with inverse square attenuation of light intensity. for the Milky Way. Vertical axis is speed of rotation about the galactic center. Horizontal axis is distance from the galactic center. The sun is marked with a yellow ball. The observed curve of speed of rotation is blue. The predicted curve based upon stellar mass and gas in the Milky Way is red. Scatter in observations roughly indicated by gray bars. The difference is due to dark matter or perhaps a modification of the law of gravity. ]] Attenuation by the space Unit time areal density of momentum is normally dependent on Inverse square of distance for perfect vacuum without any absorption, scattering and reflection by dark matter. Optical attenuation by Solid is described by the factor of exp(-kr). Although 1/rr factor is abnormal for opotics. density variation of dark matter from the astronomic object isn't negligible and is proportianl to -ln(rr)/r which is primitive. Function -2lnr/r has a minimum about -0.74 at r=2.73 and asymtotically approaches to 0. Density function inbetween the astronomical objects may be rewritten. D®/D_0 = C_l - 2 lnr/r where C_l > 0.74 and r is also normalized value of distance r=d/ r_0 To find r_0 & D_0 ; out is very necessary to proceed. Temperature and mass density against altitude from the NRLMSISE-00 standard atmosphere model shows that local minimum is between 100km and 160km. And conventional density of dark matter decreases moontonically with radius. File:LunarPhotons.png| APOLLO Collaboration photon pulse return times File:Darkmatter.JPG|density of dark matter which gives 1/rr attenuation Image:Atmospheric_pressure.JPG|Atmospheric pressure Image:Atmospheric_density.JPG|Atmospheric density Image:Atmosphere model.png|Temperature and mass density against altitude from the NRLMSISE-00 standard atmosphere model Image:Structure of the magnetosphere mod.svg|Schematic of Earth's magnetosphere. The solar wind flows from left to right. Image:Plasma scaling.svg|Density and temperature of plasma in the magnetosphere and other areas of space. Density increases upwards, temperature increases towards the right. The free electrons in a metal may be considered an electron plasmaAfter Peratt, A. L., "Advances in Numerical Modeling of Astrophysical and Space Plasmas" (1966) Astrophysics and Space Science, v. 242, Issue 1/2, p. 93-163. Image:Earthmagnetictail.jpg|A view from the IMAGE satellite showing Earth's plasmasphere using its Extreme Ultraviolet (EUV) imager instrument. Rotation curves as evidence of a dark matter halo The presence of dark matter in the halo is demonstrated by its gravitational effect on a spiral galaxy's rotation curve. Without large amounts of mass in the extended halo, the rotational velocity of the galaxy should decrease at large distance from the galactic core. However, observations of spiral galaxies, particularly radio observations of line emission from neutral atomic hydrogen (known, in astronomical parlance, as HI), show that the rotation curve of most spiral galaxies remains flat far beyond the visible matter. The absence of any visible matter to account for these observations implies the presence of unobserved (i.e. dark) matter. Asserting that this dark matter does not exist would mean that the accepted theory of gravitation (General Relativity) is wrong, and while that could be possible, most scientists would require extensive amounts of compelling evidence before considering it. The Navarro-Frenk-White profile:Navarro, J. et al. (1997), A Universal Density Profile from Hierarchical Clustering \rho®=\frac{\rm constant}{(r/a)(1+r/a)^2} is often used to model the distribution of mass in dark matter halos. Theoretical dark matter halos produced in computer simulations are best described by the Einasto profile:Merritt, D. et al. (2006), Empirical Models for Dark Matter Halos. I. Nonparametric Construction of Density Profiles and Comparison with Parametric Models \rho® = \rho_0 e^{-\alpha r^n}. Solar eclipse Gallery Solar eclipse shows Density of dark matter around the planet moon. Image:Solar eclipse set 1990-1992.JPG|1990-1992 Image:Solar eclipse set 1993-1996.JPG|1993-1996 Image:Solar eclipse set 1997-2000.JPG|1997-2000 Image:Solar eclipse set 2000-2003.JPG|2000-2003 Image:Solar eclipse set 2004-2007.JPG|2004-2007 Image:Solar eclipse set 2008-2011.JPG|2008-2011 Dust trail Image:PIA08452.jpg|Comet Image:Sig05-008.jpg|Dust trail File:Comet Parts.jpg|Diagram of a comet showing the dust trail, the dust tail (or antitail) and the gas tail. NASA File:Cometorbit.png|A comet's orbit showing the different directions of the gas and dust tails as the comet passes the Sun See also *Atmosphere *Magnetosphere *Dark matter halo References Category:Gravity wikia Category:Structure of the Earth Category:dark matter Category:attenuation